1. Field of the Invention
The present invention relates to a turbo compressor and a turbo refrigerator.
Priority is claimed on Japanese Patent Application No. 2010-087859, filed Apr. 6, 2010, the content of which is incorporated herein by reference.
2. Background Art
As a refrigerator cooling or freezing a cooling object such as water, there has been known a turbo refrigerator including a turbo compressor compressing and discharging a refrigerant gas. As disclosed in Japanese Patent Application, First publication No. 2009-185713, the turbo compressor is provided with an impeller rotationally driven by a motor and the refrigerant gas is compressed through the rotation of the impeller. In addition, the motor is accommodated in a motor casing.
Here, the motor casing includes a body portion molded in a cylindrical shape and a blocking cover molded in a planar shape and blocking both ends of the body portion. However, since the blocking cover is molded in a planar shape, there is a concern that the blocking cover resonates with the operation of the motor. In particular, if the resonance is generated in the blocking cover when the motor is operated at a specific rpm, there is a concern that noise increases or the motor casing is damaged. That is, it is difficult to increase the rpm of the motor up to a value equal to or higher than the specific rpm. Accordingly, in the turbo compressor and the turbo refrigerator of the related art, it is difficult to stably operate the motor at a high rpm.
The invention is made in view of such circumstances, and an object thereof is to provide a turbo compressor capable of stably operating a motor at a high rpm and a turbo refrigerator having the turbo compressor.